1. Field of the Invention
The present invention relates to a rotation angle controlling motor, and particularly to an oscillating motor in which positional adjustment of the origin of a main shaft can be easily made after the assembly of the motor.
The present invention relates to a measurement device for measuring a distance, a moving speed, or a moving direction by using a laser light, and particularly to a device for measuring a distance, a moving speed, or a moving direction in which the direction of an irradiated laser light and the range of scanning can be easily set, a load to an arithmetic CPU for performing calculation after receiving light is small, and measurement accuracy is high. The present invention also relates to a vehicle having the measurement device.
2. Description of the Related Art
First, a conventional rotation angle controlling motor will be described with reference to an oscillating motor as an example.
FIG. 3 is a schematic structural view showing the inside of a conventional oscillating motor. An oscillating motor 10 is such a motor that a rotation angle of a main shaft 1 can be arbitrarily controlled. Two-pole magnets 7a and 7b are cylindrically fixed to the main shaft 1 in the radial direction. Coil substrates 3a and 3b are disposed around the outer circumferences of the magnets 7a and 7b with an interval of a predetermined distance. Driving coils 5a and 5b are uniformly wound around the coil substrates 3a and 3b (the driving coil 5b is not shown). Rotation angle detecting magnets 11a and 11b for detecting a rotation angle of the main shaft 1 are disposed at the lower portions of the magnets 7a and 7b. A position detecting sensor 9 is disposed at the outer circumference of the rotation angle detecting magnets 11a and 11b with an interval of a predetermined distance.
An operation of this motor will next be described. In FIG. 3, when an electric current is made to flow through the driving coils 5a and 5b, a torque is generated between these driving coils and the magnets 7a and 7b. If an electric current is fixed to a predetermined value, the main shaft 1 stops. If the driving coils 5a and 5b are connected to each other in series and an alternating current is made to flow, it is possible to make the main shaft carry out an oscillating motion within a range of less than 180 degrees.
When the main shaft 1 is oscillated, an output in proportion to the magnetic flux density shown in FIG. 4 can be obtained from the position detecting sensor 9. Thus, if an electric current flown in the driving coil 5 is adjusted so that the output signal from the position detecting sensor 9 is made a predetermined value, it is possible to control the main shaft 1 so as to stop the shaft at a desired position. Further, if a signal from a not-shown oscillator is made an alternating current signal and is inputted into the driving coil 5, it is also possible to control the main shaft so that the main shaft is simply reciprocated within a range of an angle.
In the conventional oscillating motor 10, the position detecting sensor 9 and the rotation angle detecting magnets 11a and 11b are disposed in the inside of a not-shown motor case 15. Thus, the positional adjustment of the origin of the main shaft 1 must be carried out at the time of assembling the oscillating motor 10. This positional adjustment of the origin is carried out such that a reference current is made to flow through the driving coil 5 in the state where the oscillating motor 10 is temporarily assembled, and a deviation of the main shaft 1 from the origin is compensated by, for example, moving the driving coil 5. Thus, the adjustment requires an operation time, and there is a fear that the adjusted position is slightly deviated after the completion of assembly. Besides, there is a fear that the position of a not-shown screw hole for attachment of the motor is deviated from the designed position;, or cable releasing positions of the driving coil 5 and the position detecting sensor 9 are deviated from the designed positions.
A conventional device of measuring a distance by using a laser light will next be described.
There is conventionally a device of measuring a distance between a moving car and the car ahead by using a laser light. This conventional device adopts the following system.
System 1 (not shown):
A laser light source radiates a laser light to a reflector attached to a rear portion of the car ahead, and a light receiving portion receives the reflected light. Here, the reflector is normally disposed at the rear portion of a car or a bicycle to diffusely reflect the light from the headlights of a backward car. Based on the irradiated light and the reflected light, the distance between an objective car and the car ahead is calculated by the operation of a time difference therebetween, a phase difference therebetween, a Doppler effect, a frequency correlation, and the like.
System 2:
As shown in FIG. 6, a link mechanism 33 is attached to a driving portion 32 such as a DC motor or a stepping motor to oscillate a reflecting mirror 17. By this, a laser light is made to perform scanning within a range of a predetermined angle, and the distance between an objective car and the car ahead is calculated by operations.
System 3:
As shown in FIG. 7, a polygon mirror 35 is connectively fixed to a main shaft 34 of a driving portion 32. Then, the main shaft 34 is made to rotate in one direction. A plurality of mirror surfaces 36 are disposed on the outer circumference of the polygon mirror 35. When the mirror surface 36 is rotated, the laser light is made to perform scanning in a range of a predetermined angle.
However, in the above described system 1, since the directivity of a laser light is high, there is a fear that if the car ahead moves either right or left, the detection can not be made. In the system 2, there is a fear that the accuracy of an oscillating angle becomes inferior due to the backlash of the link mechanism 33. Besides, there are defects that since the link mechanism 33 is disposed in addition to the driving portion 32, the volume of the device becomes large, and the device becomes expensive by the cost of the link mechanism 33. In the system 3, sine the polygon mirror is constituted by the plurality of mirror surfaces 36, accuracy between mirror surfaces is required. Further, since the positions of the mirror surfaces 36 are away from the center of the main shaft 34, the position where the laser light is reflected at the mirror surface 36 is moved together with the rotation of the mirror surface 36. Thus, there is a defect that it is necessary to correct the reflected light, and a great deal of calculation is required for the correction, so that a load to an arithmetic CPU is large. Further, there is also a defect that since an arrangement angle of the mirror surface 36 viewed from the center of the main shaft 34 is determined at a constant value, a range of scanning can not be changed.